China's aviation engines still have a long way to go.I have a feeling if Vectis is not the secret program, then the secret program will be some kind of large B-2 sized ISR drone similar to what China is doing.
At this point I don't see any avenue of Aviation tech where China is behind. In most cases, whatever China comes up with, US will be a slow follower with higher cost, lower quality/capability, less ability to mass produce.
China has surpassed the US in Ground Force tech, Air defense tech, rocket force tech, Air force tech. The only remaining area where US is still ahead is naval tech due to Carriers and submarines.